He would get a $1 million, one-year contract if added to the 40-man roster and have the chance to earn performance bonuses based on games finished.
Guardado was 3-3 with four saves and a 3.65 ERA in 55 appearances for Texas last season before being traded Aug. 25 to Minnesota, the team for which he was a two-time All-Star.
The 38-year-old Guardado was a key part of the Rangers bullpen last season, mainly as a setup man. He converted all four of his save chances when he took over as the closer briefly after C.J. Wilson had season-ending elbow surgery and before he was traded.
Guardado's 860 career appearances over 16 seasons with four teams are third-most among active left-handers in the majors. He has 187 career saves, 14th among active pitchers with Billy Wagner (385) as the only active left-hander with more.